1. Field of the Invention
The present invention relates to a camera module package including an image sensor module which is used in digital cameras, mobile equipments or various monitoring devices, and more specifically, to an ultra-small-sized camera module package which can obtain an excellent result at a falling test even when an ultra-slim image sensor is used.
2. Description of the Related Art
As the information communication technology rapidly develops, data communication speed is improved, and an amount of data communication is expanded. Further, an imaging device such as a CCD image sensor or CMOS image sensor is mounted on mobile electronic equipments such as mobile phones or notebooks, and thus image data as well as text data can be transmitted in real-time, the image data being taken by a camera module.
Recently, as mobile terminals tend to be miniaturized, it is urgently required to reduce the size of each part. Based on that, the mobile communication technology and the technique for electrical parts have been continuously developed. Particularly, as mobile phones having cameras mounted thereon tends to be reduced in size and thinned, a camera module package is also required to be reduced in size and thinned.
Elements determining the height of such a camera module package include a height from the upper surface of an image sensor to the upper surface of a lens and a thickness from the upper surface of the image sensor to the lower surface of an image sensor module. The height from the upper surface of the image sensor to the upper surface of the lens is determined by an applied sensor and lens design, and the thickness from the upper surface of the image sensor to the lower surface of the image sensor module is largely determined by a packaging method applied at the time of an assembling process.
As a method of packaging an image sensor for camera, there are provided a flip-chip COF (Chip On Film) method, a wire-bonding COB (Chip On Board) method, and a CSP (Chip Scale Package) method, among which the COF method and the COB method are widely used.
The COB method is a similar process to that of an existing semiconductor production line and has higher productivity than other packaging methods. However, since wire should be used for the connection with a PCB, the size of the entire module increases and an additional process is needed. Further, the thickness of the wire-bonded PCB is included in the thickness of an image sensor corresponding to the height from the upper surface of the image sensor to the lower surface thereof. Therefore, it is unfavorable in terms of the height of the image sensor module.
In the COF method, a space for attaching wire is not needed. Therefore, the area of a package and the height of a lens barrel can be reduced. Further, since a thin film or flexible printed circuit board (FPCB) is used in the COF method, a reliable package which endures an external impact can be manufactured and the process thereof is relatively simplified. Moreover, the COF method satisfies such a tendency that signals are processed at high speed, high density is required, and multiple pins are needed.
Hereinafter, a conventional camera module package manufactured by using the COF method will be described, and the problems thereof will be examined.
FIG. 1 is a front view of a camera module according to the COF packaging method.
In the COF packaging method, an image sensor is attached on one surface (lower surface) of an FPCB 300 provided with a window through which light transmitted through a lens section can pass, as shown in FIG. 1. Then, an IR filter 330 processed to have a predetermined size is attached on the surface (upper surface) opposite to the lower surface of the FPCB 330 on which the image sensor 320 is attached. After that, coupling and bonding is performed so that the outer periphery of the IR filter 330 attached to the FPCB 300 is closely attached to the inner periphery of a lower opening of the housing 200 including the lens section 100, with the outer periphery being set to a guide surface.
In general, the thickness of an image sensor used in such a COF packaging method is about 675 μm. Recently, as a semiconductor technology develops, an ultra-slim image sensor having a height of about 200 μm is used. However, when the thickness of an image sensor is drastically reduced in order to make an image sensor module ultra-slim, a chip can be damaged by stress which is applied to the image sensor at reliability evaluation such as a falling test.
In relation to the durability of a camera module package, Japanese Unexamined Patent Application Publication No. 2001-128072 and Korean Laid-Open Patent Publication No. 2003-003887 have disclosed that, when an image sensor is flip-chip bonded to an FPCB, a reinforcing member is bonded to the FPCB by an adhesive or the like so as to secure the strength of the board.
In such a technique for securing the strength of the board itself, however, the flip-chip bonded image sensor is directly exposed outside. Therefore, reliability problems such as damage of a chip still remain.
Further, in a conventional COF packing method, such elements as multilayer ceramic capacitors (MLCC) cannot be mounted so as to be positioned inside the housing of the camera module because of the IR filter attached to the FPCB, but are inevitably mounted so as to be positioned on the same surface as the surface, on which the image sensor is attached, or outside the housing. As a result, the required FPCB increases in size, thereby increasing the size of the entire image sensor module.